In conventional magnifying apparatus for gems having cut facets, the gem is illuminated with white light using a dark field illumination apparatus. Images of the cut facets of a gem produced by this radiated light beam are then reproduced with a magnifier, video display or video printer. The following provides an explanation of a conventional apparatus using a video display or video printer, which has been used quite frequently in recent years. The conventional dark field illumination apparatus in FIG. 6 is provided with a forming opening 2 in the upper surface of case 1. A douser 4 is installed between the light source lamp 3 and the opening 2 so that the light beams of the light source lamp 3 installed within case 1 do not reach opening 2 directly. The inner surface of case 1 is furthermore made to reflect the light beams of light source lamp 3.
Gem 5, such as a diamond, wherein cut facets are formed, is attached by support arms at the upper portion of the opening 2, and video camera 6 for photographing this gem 5 is installed on the opposite side from opening 2.
Thus, the light beams emitted from light source lamp 3 do not reach gem 5 directly, but rather only light beams reflected on the inner surface of case I illuminate gem 5. These light beams are then photographed by video camera 6 corresponding to the state of the cuts of the gem, magnified and then reproduced with a video display or video printer.
The quality of the cuts of the gem, the presence of impurities within the gem and transparency can be evaluated using this image depicted on the video display or video printer, thereby allowing appraisal and ranking of the gem.
In this type of magnifying apparatus for gems having cut facets formed therein, since the light and dark pattern of white light according to the cuts of the gem is only produced on a video display or printed out with a video printer, the border lines of adjacent cut facets are not shown. Thus, it is difficult to evaluate the quality of the gem, and particularly gem proportions and the ranking of its cut. In addition, it also has the disadvantage of having difficulty in adequately arousing the interest of customers during sales of gems and so forth.